Sunday, July 24, 2011

My turntable (Acoustic Signature Challenger) came with a 12V ac synchronous motor and outboard power supply. The power supply unit produced a smooth sine wave (in fact : two waves some 90 degrees apart) as confirmed using an oscilloscope. Opening the unit revealed that the timing is by RC circuit and switching in/out different combination of R and/or C to change the frequency to either 50Hz or 66.7Hz (for 33.33rpm or 45rpm platter speeds). Fine tuning of the frequency is by trimming the variable resistors (one trimmer for each speed). Disappointed that the timing circuit wasn't quartz/crystal locked that I expected (RC timing circuits are not known for its accuracy or stability), I decided to build one myself. Searching for sine wave generators led me to DDS (Direct Digital Synthesis) and without having to build one from scratch using a PIC and programming in the codes, I just purchase one from eBay for about USD45. This DDS can output sine, square, triangular waveform up to 2V peak to peak from a few Hz up to 2MHz with 0.01Hz resolution - offering more than what I required. I thought, with 20MHz crystal clock, outputting just 50Hz (a division of some 400,000 times) - its frequency would be highly accurate and stable.

Next step would be to amplify this signal (of about 1V AC sinewave) to the required 12VAC. I just followed this idea : TTPSU and built a class B power amp (5W) using TL072 Op Amp and BD911/912 power transistors, with +/- 18V supply. Connect everything up and put into a plastic box, we have a complete turntable power supply for 12VAC synchronous motor. The 2nd 90 degree out out phase waveform was created using a 4.7uF capacitor (no-polarity). Later, I may add an op amp 'integrator' to derive the cosine wave (90deg) and another set of power amp as an alternative to the capacitor solution. Sine waveform checked with oscilloscope - very fine, distortion not checked. Tested with the motor it works on first try. And with the motor driving the platter, the speed of 33.33rpm was achieved when the frequency is set at 48.90Hz (due to pulley /platter diameter combination and manufacturing tolerances). Satisfaction? You bet.

Sunday, July 17, 2011

Hifiduino updated the software codes to version B09c, fixing some bugs and now my DAC can be controlled by a Apple remote control (only the volume & muting though). The LCD displays a fresh look as shown in the photo below. Uploading the program code is easy - via USB and using Arduino's own software and you can easily edit the codes to display the 'welcome screen' (when powered on) of your choice - for eg. your own name , etc.

When in use, the sampling rate (SR) is displayed to the last digit and is not 'rounded' to 100s, so you get figures like 44105 or 44095 (below) when playing 44.1kHz, which is acceptable considering it is only an error of 5Hz. What I meant is you won't get exactly 44100, 88200, 96000 or 192000 on the display unless you change the software code to round off to the nearest 100. Using different sources will result in slightly different figures but we don't know the actual absolute figure because there are many sources of error from the sources (cd player or Musiland) clocks error, Arduino clock error, the Buffalo clock error. If all else remain constant, it can tell the relative clock rate of different sources (faster or slower by comparison only - not the true absolute clock rate). Sonically, the most important thing is the stability of the clocks - frequency drift (with time/temperature) and jitter. Unless we use a master word clock to synchronise all the clocks in the chain, or better still use atomic clock, maybe next time .........

Saturday, July 16, 2011

I use Foobar2000 (a free Windows digital audio player) to playback high resolution digital audio files purchased or downloaded from the web. Foobar can be user customised and plays most digital audio files well up to 24bit 192kHz rate. Initially I connect the PC directly to the DAC via SPDIF, after configuring the output to SPDIF but I wasn't sure if the PC alters the sampling rate or not. I got a good value, China made, Musiland Monitor 01USD (instead of the more well known and expensive M2tech Hiface) to do the job of outputting SPDIF. Using its own drivers and connecting to the PC(notebook) via USB cable it can output SPDIF in its original sample rate and bit depth - exactly what I wanted. Connected to the Buffalo II DAC with "Hifiduino" display confirms that, showing 192038 when playing 192kHz HD audio files. Tried with files of resolution 88.1kHz and 96kHz with no problems.

With the Apple ipod dock Onkyo ND-S1, the digital output connecting directly to the Buffalo II dac, the sampling rate was always 44.1 k, the same as when connected to my TEAC cd player.

Thursday, July 14, 2011

Got me an Arduino UNO board and started doing its basic programming tutorials and got an LCD display panel to toy with. Great to have these tools and dedicated people to learn from. I always wanted to know the actual sample rate of digital music that is fed into the DAC so I searched for solutions on the web and found this : Low cost SPDIF digital monitor. I then stumbled upon Hifiduino who provided the answers and more - it controls the settings of the Buffalo II DAC too. So, I set out to build the DAC display as described in Hifiduino following each steps carefully and cut and paste the software codes (with minor modifications to the codes and some emails to the code writer) - bingo it works! Now, I not only have a good sounding DAC but also a well featured one too.

For about a year now I have used the Buffalo II DAC for my digital music playback and I must say its my best DAC to date. The initial lead was from the information that big name DAC makers are using the 32 bit ESS9018 chip from Sabre and it sounds good but expensive. I found that they made 'evaluation kits' and people buy these kits to make DACs of audiophile grade. Then the DIY Buffalo II (now Buffalo III) from Twisted Pear Audio crops up as the most economical solution to a DAC using ESS9018 chip. The rush and very low volume supply couldn't meet demand for months but I managed to buy one last year and the rest is history.

Wednesday, July 13, 2011

My restored Sony Open Reel Tape Deck, besides cleaning, polishing and oiling, the rubber pinch rollers were machine ground by specialists. The old transistors in the preamp circuits were replaced with new ones and this significantly reduced the transistor noise (hiss) to an inaudible level. Without tapes to really test out the machine, I purchased a few from eBay sellers, choosing only 7-1/2 ips (inch per second) tapes. Sounds wonderfully analogue - frequency response was acceptable and the recording is as good as the equipment and technology could reach back then. As the unit can go up to 15ips it would be good to lay hands on such a recording (hard to find) - as the Tape Project tapes are definitely out of reach for me.....

Sunday, March 27, 2011

Then the desire to make digital copies of our vintage vinyl LPs that were not available in cd format. Got myself not one but 2 cd recorders: Sony CDR-W66 and the Marantz CDR630 below.

The Sony is equipped with all the inputs and outputs you can think of - analogue and digital (both RCA and XLR). It even has word clock input and computer keyboard (for typing cd text) input, below.

The Sony has all the features that I liked and sounded wonderful, making great copies of my LPs on cds. The built-in ADC is good and the cd text feature an added advantage. So, I decided to keep it (Sony) and disposed off the Marantz. Pictured below with the old favourite TEAC VRDS-10 see how small it is.

After a couple of years, the receiver chip CS8404 of the Promitheus Audio DAC failed, replaced it by desoldering and soldering the new chip but after a few months, the chip burnt again. I decided not to replace the chip as the pcb tracks was badly damaged and some broken or detached from the board. So, I scout around for a new DAC and decided on the DIY Paradise (another local Malaysian maker) 's Monica 3. Due to revision (upgrading), it comes in 2 pcbs (probably in transition phase before the new tool pcb is ready), so I purchased one and start soldering the parts below.

The populated new version pcb (black) is pluged (4pins) onto the "old" version pcb which has the power supply regulators presoldered on it. Its another TDA1545A dac which was well reviewed.

And the whole DAC board (Monica 3) goes into the original wooden box of the Promitheus Audio DAC, using its original power supply transformers. The output transformers (on the right) are however not used. This DAC has capacitor coupling at the the outputs. This is another NOS dac and sounds as good as the reveiws say - no complaints so far, only the bass output is a shade below what I was used to.

Saturday, March 26, 2011

Then I bought a used Marantz SA-11S1 sacd player to check it out since it was a well reviewed equipment. It turned out to be too "soft" for me, although very 'clean', it lacked the 'oomph' when compared to my old TEAC VRDS-10 connected to an outboard DAC - the Promitheus Audio DAC. Hence, after just a few weeks, I disposed of the Marantz without any loses and it was sold within an hour of posting the ad online. I miss its excellent finish and solid build rarely found on lesser cd players nowadays.

Wednesday, March 23, 2011

A tiny tube(6C4) under test - good condition with all 5 filament bulbs lighted(foreground).The front panel of the 6000A is nicely clustered with vintage knobs and large panel meter.The inside : shows the 2 large vacuum tubes (rectifier tubes) and the bunch of wires connected to the transformer and the array of switches and the twin rolls of paper - tube specification charts

The linear tracking arm was attached to the Acoustic Signature turntable - more for the fun of it.

Pioneer PL-L1000 vintage turntable

Got this linear tracking direct drive turntable on eBay, but it arrived damaged but still workable. Later, bought some parts and end up with a complete turntable + a separate linear tracking tonearm. The tonearm run on rollers/track and is driven but a linear magnet and controlled by servo system using light. It has the usual automatic functions and plays 7", 10" & 12" records and stops automatically at the end of the record.

Thursday, April 2, 2009

The Hagerman Piccolo in DIY kit form arrived from USA by post today. From the photo of the pcb, the surface mounted FETs (6 pcs) are already in place. I purchased from them the 2 power supply ICs and they too were soldered on. The only components left were the capacitors and resistors. I intend to use it without the rotary switches which control gain and input loadings, so had jumpers in place of the switches S1 and S2.

I traded my Linn turntable (without arm) for a Thorhauge. It is a solid state discrete FET battery powered pre-amplifier with 26dB gain. In fact when this friend from Penang suggested it to me, I have already placed my order for the DIY kit of Hagerman Piccolo FET moving coil head amp which also recomended battery power supply.

On using the Thorhauge, I find it absolutely quite and noiseless, and eventhough the gain is high all the slight hum present when using transformer MC step up was completely gone. Changing the input loading between 10, 20, 30, 50, 100 & 250 ohms has the effect of some treble and gain boost or cut. Still have not got the optimum setting yet.

When the Hagerman Piccolo arrives, I intend to house it inside the Thorhauge and keep their individual set of inputs/outputs separate and only share a common power supply.

Wednesday, April 1, 2009

Comparing the cantilever, the Benz Micro (red body) is no different from the Rega (green) which is an MM cartridge. The Lyra's solid boron cantilever is only about half the diameter.

With only one tonearm in use and the difficulty to rotate them, not to mention the risks involved in switching cartridges often, I decide to sell the first two. Since I have a Linn Itok LVII lying around, I will mount the Denon on it and add this second tonearm to my AS turntable. Suitable components are ordered or in the process of fabrication.

Finally received my Lyra Dorian, bought used via Echoloft Singapore. My most expensive cartridge so far, it costs RM1,350 used and it is an entry level Lyra, in fact the cheapest LYRA and the stylus is from Namiki, not the usual Ogura. Talk about the embarrasing purchasing power of Malaysians using the Ringgit. Condition when received is good, and tested well on my AS turntable and Kuzma arm. The frequency response at both ends seems to be better than the Denon 103R and more detailed. The only setback is it sensitivity to groove noise making it unsuitable to play older/noisy records and the output is rather high - in fact too high such that I have to figure out how to reduce the MC step up gain without degrading the sound. The pictures below tell a thousand words.......

Thursday, February 26, 2009

The pictures show how the arrangement in the same room evolved over time. The AV equipment remains the same : BENQ PE7700 dlp projector and SONY AV333ES amplifier driving Arcaydis AK3 and center speakers and Wharfedale rear speakers.

I still keep the classic old favourite : Linn LP12 turntable that has been fitted with many tonearms and cartridges over some 25 years. Here, I have pictures of it with Fidelity Research FR-12 arm, Linn Basik LVX (SOLD) and Linn Ittok LVII (current arm). The Ittok has been Cardas rewired and a joint removed.

Tuesday, February 10, 2009

I have a pair of these Mullard tubes installed in my phono stage (SOFTONE Model 4) replacing the stock tubes - SOVTEK 12AX7LPS. These NOS Mullard M8137 are also milliatry specs CV4004 (equivalent to 12AX7) and are much sought after for pre amp use.